2. Today’s agenda
• DBMS Languages
▫ Data Definition Language (DDL)
▫ Storage Definition Language (SDL)
▫ View Definition Language (VDL)
▫ Data Manipulation Language (DML)
• DBMS Interfaces
Database Management
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3. DBMS Languages
• Data Definition Language (DDL): In many DBMSs
where no strict separation of levels is maintained, DDL is
used by the DBA and database designers to define both
conceptual and internal schemas.
• DBMS will have a DDL compiler whose function is to
process DDL statements in order to identify descriptions
of the schema constructs and store the schema
description in the DBMS catalog.
• Where a clear separation is maintained between the
conceptual and internal levels, the DDL is used to specify
the conceptual schema only.
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4. Storage Definition Language (SDL)
• Is used to specify the Internal schema
• The mapping between two schemas may be
specified in either DDL or SDL
• For the true three-schema architecture we need
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Database Management
Systems
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5. View Definition Language (VDL)
• Is used to specify the user view
• Mapping the view in conceptual schema
• In most DBMS DDL is used for both conceptual
and external schemas
Database Management
Systems
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6. DBMS Languages
• Data Manipulation Language (DML): Used
to specify database retrievals and updates.
• DML commands (data sublanguage) can be
embedded in a general-purpose programming
language (host language), such as COBOL, C or
an Assembly Language.
• Alternatively, stand-alone DML commands can be
applied directly (query language).
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7. DBMS Languages
• High Level or Non-procedural Languages:
also called set at a time, e.g., SQL, are set-
oriented and specify what data to retrieve than
how to retrieve. Also called declarative
languages.
• Low Level or Procedural Languages: also
called record-at-a-time; they specify how to
retrieve data and include constructs such as
looping.
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8. DBMS Interfaces
• Menu-Based interfaces for Web Clients or
Browsing
• Form-Based Interfaces
• Graphical User Interfaces
• Natural Language Interfaces
• Interfaces for Parametric Users
• Interfaces for the DBA
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9. Menu-Based Interfaces for Web Clients
or Browsing
• List of options presented to the users called
menus that lead the user through the
formulation of a request
• No need to memorize the specific command or
syntax of a query language
• Query is composed step-by-step by picking
options from a menu that is displayed by the
system such as pull down menus.
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10. Form-Based Interfaces
• Displays a form to each user
• Fill the entries in the form (entering or
retrieving data)
• Designed for Naïve users
• Forms specification languages (SQL* forms,
Oracle Forms) help programmers to specify such
forms
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11. Graphical User Interfaces
• Displays a schema to user in diagrammatic form
• Specify the query by manipulating the diagram
• Utilizes both menus and forms
• Uses the pointing device
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12. Natural Language Interfaces
• Accepts request written in English
• Attempt to understand the request
• Has its own schema
• Include dictionary important words
• Produces the high-level query and submitted to
the DBMS
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13. Speech Input and Output
• Limited use of speech as an input query and
speech as an answer to a question or result of a
request is becoming commonplace.
• Applications with limited vocabulary such as
telephone directory, flight arrival/departure,
and bank account information are allowing
speech for input and output to enable ordinary
folks to access this information.
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14. Interfaces for Parametric Users
• Small steps of operations which have to perform
repeatedly i.e., Bank tellers
• Design some special interface
• Small set of abbreviated commands
• Proceed with a minimal number of keystrokes
(function keys)
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15. Interfaces for the DBA
• Most database systems contain privileged
commands that can be used only by the DBA's
staff.
• Creating accounts, granting authorizations
• Setting system parameters
• Changing schemas or access path
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